![background image](http://html1.mh-extra.com/html/nidec/5200250/5200250_power-installation-manual_1687772066.webp)
66
Unidrive M/HS Frame 5 to 6 Power Installation Guide
Issue Number: 9
4.10.3
Braking resistor software overload protection
The drive software contains an overload protection function for a braking resistor. In order to enable
and set-up this function, it is necessary to enter three values into the drive:
•
Braking Resistor Rated Power
(10.030)
•
Braking Resistor Thermal Time Constant
(10.031)
•
Braking Resistor Resistance
(10.061)
This data should be obtained from the manufacturer of the braking resistors. The braking resistor
thermal time constant can be calculated from resistor data sheet values using the following equation:
Pr
10.039
gives an indication of braking resistor temperature based on a simple thermal model. Zero
indicates the resistor is close to ambient and 100 % is the maximum temperature the resistor can
withstand. A ‘Brake Resistor’ alarm is given if this parameter is above 75 % and the braking IGBT is
active. A Brake R Too Hot trip will occur if Pr
10.039
reaches 100 %, when Pr
10.037
is set to 0
(default value) or 1.
If Pr
10.037
is equal to 2 or 3, a Brake R Too Hot trip will not occur when Pr
10.039
reaches 100 %,
but instead the braking IGBT will be disabled until Pr
10.039
falls below 95 %. This option is intended
for applications with parallel connected DC buses where there are several braking resistors, each of
which cannot withstand full DC bus voltage continuously. With this type of application it is unlikely the
braking energy will be shared equally between the resistors because of voltage measurement
tolerances within the individual drives. Therefore with Pr
10.037
set to 2 or 3, then as soon as a
resistor has reached its maximum temperature the drive will disable the braking IGBT, and another
resistor on another drive will take up the braking energy. Once Pr
10.039
has fallen below 95 % the
drive will allow the braking IGBT to operate again.
See the
Parameter Reference Guide
for more information on Pr
10.030
, Pr
10.031
, Pr
10.037
and
Pr
10.039
.
This software overload protection should be used in addition to an external overload protection
device.
4.11
Ground leakage
The ground leakage current depends upon whether the internal EMC filter is installed or not. The
drive is supplied with the filter installed. Instructions for removing the internal filter are given in
section 4.12.2
With internal filter installed:
Size 5 to 6:
28 mA* AC at 400 V 50 Hz
30 µA DC with a 600 V DC bus (10 M
)
* Proportional to the supply voltage and frequency.
With internal filter removed:
<1 mA
When the internal filter is installed the leakage current is high. In this case a permanent
fixed ground connection must be provided, or other suitable measures taken to prevent a
safety hazard occurring if the connection is lost.
Pr 10.031
Resistor pulse power rating x Braking time
Resistor continuous power rating
--------------------------------------------------------------------------------------------------------------------------
=
WARNING
Summary of Contents for 5200250
Page 110: ...0478 0255 09...